Electroretinogram responses and refractive errors in patients with a history of retinopathy prematurity

Ametropias, particularly myopia, and mild retinal dysfunction are found in eyes with a history of retinopathy of prematurity. The retina is an important controller of refractive development. The aims of this study were to find out whether altered measures of retinal function and ametropias are associated and to consider mechanisms by which the retina might control refractive development. Nine infants and children with a history of stage 1, 2 or 3 retinopathy of prematurity and known courses of refractive development were studied. Spherical equivalents at the time of the electroretinogram ranged from +5.50 to -9.00 diopters. Rod photoresponse characteristics were derived from the a-wave, and postreceptoral components were also analyzed with calculation of the sensitivity and saturated amplitude of the b-wave, the sensitivity of oscillatory wavelet OP2, and average amplitudes of OP3 and OP4. In hyperopic and myopic patients alike, the saturated amplitude and gain of the rod cell response were attenuated. In all patients, b-wave sensitivity was low, but in most there was little effect on saturated b-wave amplitude. In patients with courses toward myopia, the amplitude of OP4, an 'OFF' signal, is relatively more attenuated than that of OP3, an 'ON' signal. OP4 is relatively larger in patients with courses toward hyperopia. The OP results suggest that an imbalance of 'ON' and 'OFF' activity in the retina is associated with development of ametropias in retinopathy of prematurity.